Self adjusting nut assembly for wheel retainment

ABSTRACT

A self-adjusting nut assembly used to adjust the race-bearing relationship in a vehicle front wheel assembly in order to eliminate radial and axial play between the hub and the spindle of the wheel assembly, the nut assembly comprising a nut having integral camming ramps on its inboard face which cooperate with similar camming ramps on an interior member slidably mounted on the wheel spindle, the interior member being maintained in assembly with the nut within a shroud with a coil spring secured to the nut and the interior member to produce the desired rotational movement between the nut and the interior member which results in these elements being spread apart.

United States Patent [191 Play i 1 SELF-ADJUSTING NUT ASSEMBLY FOR WHEELRETAINMENT [75] Inventor: Charles N. Hay, Sandusky, Ohio [73] Assignee:General Motors Corporation,

Detroit, Mich.

[221 Filed: July 6, 1971 [211 Appl. No.: 159,756

FOREIGN PATENTS OR APPLlCATlONS Germany 308/211 July 17, 1973 PrimaryExaminerCbarles J. Myhre Assistant ExaminerFrank Susko Att0rney-J. L.Carpenter et al.

57 ABSTRACT A self-adjusting nut assembly used to adjust the racebearingrelationship ina vehicle front wheel assembly in order to eliminateradial and axial play between the hub and the spindle of the wheelassembly, the nut assembly comprising a nut having integral cammingramps on its inboard face which cooperate with similar camming ramps onan interior member slidably mounted on the wheel spindle, the interiormember being maintained in assembly with the nut within a shroud with acoil spring secured to the nut and the interior member to produce thedesired rotational movement between the nut and the interior memberwhich results in these elements being spread apart.

3 Claims, 3 Drawing Figures SELF-ADJUSTING NUT ASSEMBLY FOR WHEELRETAINMENT This invention relates to a self-adjusting nut assembly andspecifically to a self-adjusting nut assembly for adjusting therace-bearing relationship in a wheel bearing assembly.

To obtain maximum performance of tapered bearings in conventionalpassenger car front wheel mountings and some rear wheel mountings, it isimperative that proper bearing adjusments be made after asssmbly of thebearings and wheel hub. In making these adjustments, a certain amount ofjudgment is required by the assembler as to how tightly to pull up theconventional wheel retaining nut against the bearings on the wheelspindle. In addition, during the manufacturing of the various componentsfor such a conventional wheel assembly, proper engineering and machinestandards must be met in order to permit proper bearing adjustment insuch an assembly.

It is therefore the principal object of this invention to improve a nutassembly for use in a vehicle wheel assembly in which the race-bearingrelationship in the wheel bearing assembly is automatically adjusted inorder to eliminate radial and axial play between the hub and the spindleof the wheel mounting.

Another object of this invention is to provide a selfadjustment nutassembly for vehicle wheel retainment whereby the race-bearingrelationship in the wheel bearing is properly and automatically adjustedby means of the self-adjusting nut assembly.

, These and other objects of the invention are attained by means of aself-adjusting nut assembly comprising a nut having integral cammingramps on its inboard face which cooperate with similar camming ramps onthe outboard face of an inner member, the nut being secured to thespindle on which it isused, with a housing or shroud enclosing a portionof the nut and the interior member, and with a coil spring secured tothe nut and the interior member to bias the interior member rotationallywith respect to the nut to urge the nut and interior member ramps apartto effect and maintain proper adjustment of the wheel bearings.

For a better understanding of the invention, as well as other objectsand further features thereof, reference is had to the following detaileddescription of the invention to be read in connection with theaccompanying drawings, wherein:

FIG. 1 is a sectional view of a portion of an automotive front wheelassembly incorporating a self-adjusting nut assembly constructed inaccordance with the invention;

FIG. 2 is an exploded perspective view of the spindle and nut assemblyof FIG. I; and,

FIG. 3 is a view similar to that of FIG. 1 but incorporating a secondembodiment of the self-adjusting nut assembly of the invention.

Although the self-adjusting nut assembly of the invention could be usedwith other forms of structures, it is shown in FIG. 1 as used on anautomotive front wheel bearing, spindle and wheel assembly. Referringnow to FIG. I, a nonrotatively mounted shaft or wheel spindle positionedby spindle support spacer 12 serves as a support for a wheel, the hubportion 14 of which is only shown in this figure. The hub 14 isrotatably mounted on the spindle 10 by means of a pair of opposedtapered inboard and outboard rollerbearings 16 and 18, respectively. Forproper operation of such an assembly, axial and radial play must beeliminated between the hub 14 and the spindle 10.

To effect this in part, as shown, the outer race of the bearing 16 abutsa shoulder 14a of the hub at its righthand side while the inner race ofthis bearing abuts on its left-hand side, as seen in FIG. I, a shoulder10a on the spindle 10. In addition, the outer race of the bear ing 18abuts on its left-hand side, as seen in this figure, a shoulder 14b ofthe hub 14. By properly adjusting the axial position of the inner raceof bearing 18 in abutment against a bearing retaining washer 20, axiallyslidably mounted on the reduced end of the spindle l0 and fixed againstrotation thereon by engagement of the inward radial lug 22 of thiswasher into a suitable axial extending slot 24 provided in the spindlefor this purpose, the radial and axial play between the hub 14 and thespindle 10 can be eliminated.

Now in accordance with the invention, there is provided a self-adjustingnut assembly which, when threaded to the end of the spindle, willautomatically accomplish this adjustment of the axial position of theinner race of bearing 18. t

For use with a wheel spindle, of the type shown in FIG. 1, having anabutment shoulder 11 between its threaded portion 26 and its reducedportion 10b supporting bearing 18, there is provided a self-adjustingnut assembly, generally designated 30, constructed in accordance withthe embodiment illustrated in FIGS. 1 and 2. As shown in these figures,the nut assembly 30,

consisting of four elements secured together to provide a unit-handlednut assembly, includes nut32, an interior member 34, a coil spring 36and a housing or shroud 38.

The nut 32, which may be die-cast, includes a castellated hex nutportion 42 with a plurality of slots 44 at the end thereof and with athreaded bore 40 therethrough, and an intermediate radially outwardextend ing annular flange 46 and an end collar 48 with a bore 50 thereinof a diameter slightly larger than the outside diameter of the reducedportion 10b of the spindle, the threaded bore 40 and the bore 50 meetingcoaxially with a shoulder 52 therebetween. The free end or lefthand endof the collar 48, as seen in FIG. 1, which is the inboard end of nut 32,includes in the embodiment shown three camming ramps or cam surfaces 54for a purpose to be described.

The interior member 34, in the form of a ring face cam, includes anannular collar 56, slidably receivable on the reduced portion 10b ofspindle 10, provided with a plurality of circumferentially spacedradially outward extending lobes 58. The inboard or left-hand endsurface of collar 56, as seen in FIG. I, is plain or flat for abutmentagainst the bearing retaining washer 20 while the opposite end oroutboard end is provided with camming ramps or cam surfaces 62 forcooperation with the matching ramps or cam surfaces 54 of nut 32 toeffect and maintain axial displacement of the interior member 34relative to the nut 32 in a manner to be described.

A coil spring 36 is used to normally rotatively bias the interior member34 in a direction relative to the nut 32 to cause rotational motion ofthe interior member 34 with respect to the nut 32 in an up-rampdirection to cause maximum axial extension of these elements withrespect to each other within the limits permitted by the housing orshroud 38, as described hereinafter. The coil spring 36, which is placedin tension before assembly, is mounted to encircle the collar 48 of nut32 and a portion of the interior member 34 with one end of the springengaged in a suitable slot 47 in the flange 46 of nut 32 and theopposite end of the spring is engaged against a lobe 58 of interiormember 34 to normally bias the interior member 34, in the embodimentdisclosed, in an up-ramp or clockwise direction as indicated by thearrow in FIG. 2, with respect to the nut 32.

It can be seen from the foregoing that relative rotation of interiormember 34 with respect to nut 32 in the opposite direction will resultin down-ramp movement thus shortening the axial extension of theseelements. In addition, the angle of the ramps or cam surfaces 54 and 62on these elements are so selected that these elements will frictionallylock against any axial force ap plied against these elements in adirection which would otherwise shorten their axial extension.

To provide for unit-handling of the nut 32, interior member 34 andspring 36, and to limit the axial movement between the nut 32 and theinterior member 34, these elements are enclosed and retained loosely inassembled proper relationship with respect to each other by means of ahousing or shroud 38. The housing or shroud 38, as seen in theunassembled view in FIG. 2, is in the form of a sheet metal stepped tubehaving tubular portions 62 and 64 joined together by a radial shoulder66. The free end of the tubular portion 62 is partially closed by aradially inward extending annular flange 68, the inner diameter of whichis less than the outer diameter of the lobes 58 of the interior member34.

In assembly, the interior member 34, the pretensioned spring 36 and thenut 32 are inserted into the shroud 38 through its tubular portion 64and then an end portion of the tubular portion 64 is crimped over theannular flange 46 of nut 32 to provide an outboard retaining flange 70,as shown in FIG. 1. The axial length of the shroud between the flanges68 and 70 is such so as to prevent full size or up-camming of the camsurfaces on the nut 32 and the interior member 34 with respect to eachother to prevent unwinding of the previously pre-tensioned coil spring36. With this arrange ment, the axial extension of the interior member34 with respect to nut 32 is limited as defined by the limitationspermitted by the crimped housing or shroud 38.

In final assembly to the wheel assembly, as shown in FIG. 1, the nutassembly 30 is screwed onto the spindle by means of the threaded bore 40of nut 32 engaging the threaded portion 26, until the shoulder 52 in nut32 engages the shoulder 11 on the spindle. The design of the wheelassembly and nut assembly is such that before the nut 32 is seatedagainst the shoulder 11 on spindle 10, the plain face surface 60 of theinterior member 34 contacts the bearing retaining washer somewherewithin the tolerance build-up range of the spindle, bearings and hubassembly. When this occurs, the frictional force between the bearingretaining washer 20 and interior member 34 stops the latter from turningso that further rotation of the nut 32 causes relative rotation betweenit and the interior member allowing down-ramp movement and axialshortening of these elements until the nut seats against the shoulder llof spindle l0.

Thus, when threading the nut assembly onto the spindle, the bearingretaining washer 20 first moves into abutment with the inner race ofbearing 18 and takes up stack-up tolerances of the wheel bearings andspindle assembly. When these stack-up tolerances have been eliminated,the frictional forces between the interior member 34 and the bearingretainer 20 will prevent further rotational movement of the interiormember, so that further rotation of the nut 32, until it engages theshoulder ll, will cause relative rotation between the nut 32 andinterior member 34 allowing down-ramp movement between these twoelements. That is, the ramp surfaces 54 and 62 slip with respect to eachother, thus decreasing the axial dimension across these elements untilthe nut 32 sets against the spindle shoulder 11. After this, the nut 32is merely backed off, if necessary, to expose a hole 28 in the spindleso that a cotter pin 72 can be inserted through a slot 44 in thecastellated end of the nut 32 and into this hole whereby the nut 32 isfixed against further rotation on the spindle 10.

The ramp angles of ramps 54 and 62, previously described, producesufficient friction to prevent axial thrust from the inner race ofbearing 18 to produce down-ramp slippage and a further decrease in theaxial length across nut 32 and interior member 34. Thus, in application,it is only necessary to apply the nut assembly 30 to the wheel spindlel0, draw the nut 32 up against the spindle shoulder 11 and then back itoff to expose hole 26 for cotter pin 72 insertion therein for safety. Noother adjustment is necessary. The cover 74 is then secured to the hub14 to finish the wheel assembly.

When a standard unshouldered wheel spindle 10A, as shown in FIG. 3, isused in the wheel assembly, a modified nut is required for use in theselfadjusting nut assembly of the invention. Such a modified nut 32a isshown in the embodiment illustrated in FIG. 3 wherein identical partsare identified by the same reference characters used to identify theseparts in FIGS. 1 and 2.

In this embodiment, the nut 32a includes a castellated hex nut portion420 partly closed at its free or right-hand end as seen in this figureby a radially inward extending annular flange 43, a plurality of slots44a being provided in the free end of this nut portion, and intermediateradially outward extending annular flange 46a and an end collar 48a, thefree end or left-hand end of the collar being provided with eammingramps or cam surfaces 54a which work in conjunction with the interiormember 34 having matching ramps 62 on one face thereof, as previouslydescribed. The nut 32a is provided with a threaded counterbore 40aextending therethrough to the flange 43.

The remaining components of the nut assembly shown in FIG. 3 areidentical to the components shown in the nut assembly illustrated inFIGS. 1 and 2, except for the use of the nut 320 just described. The nutassembly of FIG. 3 is assembled to the wheel spindle 10a of the typeshown in FIG. 3 in the same manner as previously described except thatin this case, the nut 32a is threaded onto the spindle until it bottomson the free end, or right-hand end, of the spindle as shown in FIG.

Thus, in assembling either embodiment of the self adjusting nut assemblyof the invention to a wheel assembly, the assembler need merely totighten down the nut, either nut 32 or 320, until it bottoms out on thespindle shaft and then he inserts a cotter pin, backing out the nut, ifnecessary, to uncover the cotter pin hole in the wheel spindle, and thetolerance stack-up of the wheel assembly is automatically eliminated.

What is claimed is:

1. In a wheel assembly having a nonrotatable spindle threaded at itsoutboard end, an inboard bearing means and an outboard bearing meansmounted on said spindle, a wheel hub rotatably supported on said spindleby said bearings, a thrust retaining washer slidably positioned on saidspindle for abutment against said outboard bearing means and aself-adjusting nut assembly threaded to said spindle for adjusting theaxial position of said outboard bearing on said spindle, saidselfadjus'ting nut assembly comprising an interior member in the form ofa cam faced collar slidably and rotatably mountable on said spindle, anut means threadingly engagable on said spindle outboard of saidinterior member, said nut means including an annular retaining meanspositioned to engage a portion of said spindle to limit the axialposition of said nut means on said spindle, said nut means having camsurfaces adapted to cooperate with said cam faced collar of saidinterior member, spring means partially encircling said interior memberand said nut means with one end of said spring engaging said interiormember and the opposite end of said spring engaging said nut means tonormally rotatively bias said interior member relative to said nut meansin an up-cam-ramp direction and, shroud means loosely encircling saidinterior member, said spring and said nut means with means on saidshroud to engage said interior member and said nut means to limit theaxial separation of said nut means relative to said interior member.

2. In a wheel assembly according to claim I wherein said nonrotatablespindle is provided with a shoulder adjacent its outboard threaded end,and wherein said nut means of said self-adjusting nut assembly isprovided with a stepped bore to form an internal shoulder defining saidannular retaining means for abutment against said shoulder on saidspindle.

3. In a wheel assembly according to claim 1 wherein said nut means ofsaid self-adjusting nut assembly is provided with a radially inwardextending annular flange at is outboard end defining said annularretaining means and adapted to abut against the outboard threaded end ofsaid spindle,

1. In a wheel assembly having a nonrotatable spindle threaded at itsoutboard end, an inboard bearing means and an outboard bearing meansmounted on said spindle, a wheel hub rotatably supported on said spindleby said bearings, a thrust retaining washer slidably positioned on saidspindle for abutment against said outboard bearing means and aself-adjusting nut assembly threaded to said spindle for adjusting theaxial position of said outboard bearing on said spindle, saidself-adjusting nut assembly comprising an interior member in the form ofa cam faced collar slidably and rotatably mountable on said spindle, anut means threadingly engagable on said spindle outboard of saidinterior member, said nut means including an annular retaining meanspositioned to engage a portion of said spindle to limit the axialposition of said nut means on said spindle, said nut means having camsurfaces adapted to cooperate with said cam faced collar of saidinterior member, spring means partially encircling said interior memberand said nut means witH one end of said spring engaging said interiormember and the opposite end of said spring engaging said nut means tonormally rotatively bias said interior member relative to said nut meansin an up-cam-ramp direction and, shroud means loosely encircling saidinterior member, said spring and said nut means with means on saidshroud to engage said interior member and said nut means to limit theaxial separation of said nut means relative to said interior member. 2.In a wheel assembly according to claim 1 wherein said nonrotatablespindle is provided with a shoulder adjacent its outboard threaded end,and wherein said nut means of said self-adjusting nut assembly isprovided with a stepped bore to form an internal shoulder defining saidannular retaining means for abutment against said shoulder on saidspindle.
 3. In a wheel assembly according to claim 1 wherein said nutmeans of said self-adjusting nut assembly is provided with a radiallyinward extending annular flange at is outboard end defining said annularretaining means and adapted to abut against the outboard threaded end ofsaid spindle.